Marantz 3800 User manual

manuaL
MODEL
3800

ERR
ae
Heaan
ER
UZ:
MODEL
3800
SERVICE
MANUAL
MARANTZ
CO.,
INC.
20525
NORDHOFF
STREET,
CHATSWORTH,
CALIFORNIA
91311
A
WHOLLY
OWNED
SUBSIDIARY
OF
SUPERSCOPE
INC.,
CHATSWORTH,
CALIFORNIA
91311

SECTION 1
GENERAL INFORMATION AND OPERATING PRINCIPLES ..... 0... ccc cece cece cece rete enennes
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3. DESCRIPTION AND OPERATION... 0.0... ccc ccc cece reece teen e tenant eeeeeene
A. FUNCTIONAL DESCRIPTION .. 0.0... ccc cece ee eee teen eee
B. OPERATING PRECAUTIONS ......... 0c cece ccc eee eee etre neat eee
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D. PHONO/MIC AMPLIFIER... .... cece cc cee een teeta eens
E. DOLBY ENCODE / DECODE PROCESSORS... 2... ... ccc ect eeetee ee eens
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G. ACTIVE FILTER NETWORK... 1... ccc cece ee eee eee ee renee
H. TONE CONTROL / TURNOVER NETWORK.......... cee eee e ee teen ete eee eee ene
4. DOLBY NOISE REDUCTION CIRCUIT ...... 0. ccc ccc cece eee eter reenter teenie
A. BASIC DOLBY PROCESS ....... cece ccc cece ee eee eee e nett e ene
B. USE OF THE DOLBY (NR) CIRCUIT AS A DYNAMIC NOISE FILTER............0.00 eee
5. TECHNICAL SPECIFICATIONS ..... 0... eee cece renee eee nee tetera ee eee
SECTION 2
MAINTENANCE ..... 0 cc cc cece ee ce eee eee cence eee ee eee eee eee eee nano e tree senna eae
1. GENERAL... 1... cic ee ce ce erent cece ete n eee e terete teen ete cee nenes
2. PREAMPLIFIER CIRCUITS TESTS AND ADJUSTMENTS ......... 00. e eee ee eee erences
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B. PRELIMINARY CONDITIONS . 2.0.2.0... ccc ccc cece eee nent eens
C. POWER CONSUMPTION VERIFICATION ......- 0.0. cece cece eee eee
D. FUNCTIONAL TEST ......... 00. cece cee eee reece nee nett a tenet eeenenee
E. MAXIMUM VOLTAGE OUTPUT ..... 0... cece cee eee teen ene enennes
F. TOTAL HARMONIC DISTORTION (THD) ...... 2... cece ce cee cece eee eens
G. HUM AND NOISE... 2... ec ccc cece eee tn cern een e ene e eee en eee een eenne
H. FREQUENCY RESPONSE (PHONO /MIC).......... 0.26 c ee eee eens
J. HIGH LEVEL SEPARATION ..... 0... cece c cece cree rece eee et eee enna e anette nae
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N. VOLUME TRACKING... . ccc cee ee renee ee eee eee teens
P. LOUDNESS CONTOUR... cece cc ee eee teen e ne nneee Aaa Ren ceays. uate
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TABLE OF CONTENTS
2-1
2-1
2-1
2-1
2-1
2-3
2-3
2-4
2-4
2-4
2-4
2-5
2-5
2-7
2-7
2-7
2-7
2-8
2-8
2-8
2-9
2-9

TABLE OF CONTENTS
( continued )
SECTION 2 PAGE
E. DOLBY RECORD MODE FREQUENCY RESPONSE........... 00. c cece cece eee ee tenes 2-9
F. DOLBY PLAYBACK MODE FREQUENCY RESPONSE .......... 20. - cee e cece eee eee eee 2-10
G. TOTAL HARMONIC DISTORTION (THD) ,..... 0... . eee cee te eee ee tee ene e eee 2-12
H. DOLBY VU METER CALIBRATION .... 0... cc ccc cece cece cece ete eet eens 2-13
J 400 Hz TONE OSCILLATOR ADJUSTMENT ....... cece cece ee eee eee ene eee 2-13
K. MULTIPLEX FILTER ADJUSTMENT... ccc cece cece eee cece eee een eens 2-13
LE. BIAS: FILTER ADJUSTMENT 02 ccc see cee tens earned nents sented bene ee eena tates 2-13
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5. REPACKING FOR SHIPMENT ......... 2 cece cece ce cece cee eee eee teen e eee eens 2-15
SECTION 3
ILLUSTRATED PARTS LIST... 2. ccc ccc c ccc cc cen ccc n cnn tec e rete rene tense ee een een eneesneeeseesese 3-1
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MODEL 3800 STEREO CONTROL CONSOLE UNIT (PREAMPLIFIER) .......-. ccc eee acne eee 3-1
CHASSIS: ASSEMBLY nie: cisysis.5 weal ole Gaye's eee iewe wie erelaied Blebin eck, Mebane eigen de tea eee 3-5
CONTROL BOARD COMPONENT ASSEMBLY ........ 0 cece e ere cece tne ete eee e ete e nee 3-6
PREAMPLIFIER BOARD COMPONENT ASSEMBLY ........ 0... cece eee ee ee eee teenie 3-9
JACK PANEL ASSEMBLY 2.01. ss disses oe Si 25 ele eee sie aje Cave CE ead ee Be 3-11
DOLBY - TAPE MONITOR BOARD COMPONENT ASSEMBLY ....... 0. cee esse cert e eee e ene 3-12
TAPE EQUALIZATION - TONE DEFEAT BOARD COMPONENT ASSEMBLY ..........-.++---- 3-15
400 Hz OSCILLATOR - DOLBY METER BOARD COMPONENT ASSEMBLY.............0000-- 3-16
INTERFACE BOARD COMPONENT ASSEMBLY ........ 0... s eee eee cece eee eee e eee eee 3-16

FIGURE NO.
1-1
1-2
1-3
1-4
a
2-2
2-3
2-4
2-5
2-10
2-11
31
3-2
3-3
34
3-5
3-6
37
38
39
TABLE NO.
1-1
1-1
2-1
2-2
2-2
2-2
LIST OF ILLUSTRATIONS
TITLE
Functional Block Diagram... 02.0.0. cece ce cece eect eeeeunuuuee
Wiring Diagrarnts ieee ocd 5 sace vrs a ets dent die eit ey wee oo S sack daiwa Shaiara leas Meese
Dolby NR Circuit Signal Processing Diagram ........... 0.00 cece eee eees
Dolby NR Circuit Signal Processing Diagram (continued) ...............0005
AC Power Control Box Connection Diagram... . 0.0... ccc cee cece cece eceees
Test Equipment Connection Diagram, Preamplifier Circuits............200e005
RIAA Equalization Curve and Standard ......... ccc cc cece cece cee cceceaeeue
Active Filter Network Characteristics ..... 0.0.0. 0c cece cece ce ceuuvetvvenee
Dolby Frequency Response, Flat Mode ...........cccc sec e ccc eeaueceesees
Dolby Frequency Response, Encode Mode..........cccceuccecucevcececece
Dolby Frequency Response, Decode Mode..........00ccccececccecsavasecs
Repacking Illustration... 0.0... ccc cc cece cee ence ne eeeenseueenes
Front Panel Controls and Indicators... 1... .. 2c. cece cece ccc cence een eeaes
Rear Panel Jacks and Connectors .... 0.0... cs ccc eee e cece neces eeeenauens
Disassembly / Reassembly Diagram.... 2.0... 0c. ceca cece cc ccecectcecece
Control Board Diagram, Circuit Side... .. 0... ccc cc eee eee ne eeaee
Preamplifier Board Diagram, Circuit Side. ...... 0... cece eae eee eee neeee
Dolby - Tape Monitor Board, Circuit Side... .. 2... cee ee cee cece ee
Tape Equalization - Tone Defeat Board, Circuit Side........... ccc cece ee aces
Tone Oscillator - Dolby Meter Board, Circuit Side.... 00... cc cee eee eee eee
Schematic Diagram ........ 0. cece cece ccc ete e ee eee ence nee nnnneege
TITLE
Recommended
Test
Equipment............ccee
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Trouble
Analysis...
2.0.2.0...
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ence
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PAGE
1-3
1-4
1-5
1-6
2-2
2-2
2-5
2-6
2-6
3-14
314
PAGE
1-8
1-9
2-3
213
214
215

Section 1
GENERAL
INFORMATION
AND
OPERATING
PRINCIPLES
|
1. INTRODUCTION
This manual was prepared for service technicians
in factory-authorized warranty repair stations and
other equally-qualified and equipped service cen-
ters. The service information contained herein is
applicable to the Model 3800 Stereo Control
Console, a stereo preamplifier manufactured by
the Marantz Company, Inc., a subsidiary of
Superscope
Incorporated,
Chatsworth,
California
91311.
2. GENERAL
Section 1 describes physically and functionally the
Model 3800 Stereo Control Console,a professional,
state-of-the-art stereo preamplifier with the Dolby
noise reduction (NR) circuit. Use, application,
performance and design features are also described.
Mechanical parts are high-quality, selections for
reliability and economy. Electronic components
in the Model 3800 circuits are precision devices
selected for their long operating life. The Model
3800 is thereby assured of providing continuous
high-quality performance.
System, functional, and detail descriptions include
the major mechanical functions and control
electronics. Specifications and capabilities are
both technical and performance related.
3. DESCRIPTION AND
OPERATION
This section is included to assist the service tech-
nician in understanding the operation of the
Model 3800. The technical data describe the basic
system functions and circuit theory of operation.
A.FUNCTIONAL DESCRIPTION
F igure 1-1 is a Functional Block Diagram of the
Model 3800 left audio channel, showing the
principal circuit elements and signal flow paths.
Additional functional and detailed reference
support data are illustrated on Figures 1-2
through 1-4: Wiring, and Dolby NR Circuit
Signal Processing Diagrams, respectively.
B. OPERATING PRECAUTIONS
WARNING:
TO
PREVENT
FIRE
OR
SHOCK
HAZARD,
DO
NOT
EXPOSE
THIS
INST
RU-
MENT
TO
RAIN
OR
MOISTURE.
CAUTION: ENSURE THAT THE TOTAL
POWER OUTPUT CONNECTED TO THE
SPEAKER SWITCHING INPUTS DOES NOT
EXCEED 250 WATTS RMS PER CHANNEL,
CONTINUOUS POWER.
CAUTION: DO NOT EXCEED THE MAXI-
MUM TOTAL POWER RATINGS OF THE
AC OUTLETS. THE POWER SWITCH AND
OTHER CIRCUITRY IN THE MODEL 3800
MAY BE DAMAGED IF SUBJECTED TO
EXCESSIVE CURRENT.
CAUTION: TURN VOLUME CONTROL CCW
TO MINIMUM BEFORE SWITCHING SPE AkK-
ER UNITS TO PREVENT POSSIBLE DAM.-
AGE TO YOUR LOUDSPEAKERS.
C. SYSTEM OPERATION
High- and low-level inputs (program sources) are
selected by the Program Selector Pushswitches
and applied in accordance with signal level.
When low-level sources are selected (PHONO or
MIC), the Program Selector Pushswitch applies
the input signal to the Phono/Mic Amp) fier
circuit and selects the proper equalization,
RIAA or Mic. The output of the Phono/Mic
Amplifier
is
then
returned
to
the
Prog-am
Selector Pushswitches where it is handle# as
another high-level input.
High-level input signals TUNER, AUX, TAPE 1,
TAPE 2 or the output of the Phono/Mic An pii-
fier are applied to the Dolby encoder/dec) der
4-1

1-2
through the buffer amplifier circuit, TAPE
REC-EQ and DOLBY Switches. The input level
to the encoder/decoder is regulated by the
RECORD LEVEL Controls. The output of the
encoder/decoder is applied to the TAPE OUT-
PUT and DUBBING OUT Jacks. With the
DOLBY Switch set to OF F, the encoder/decoder
is bypassed and the high-level input signals are
applied directly to the TAPE OUTPUT and
DUBBING OUT Jacks. The encoder/decoder
functions as a flat amplifier, an encoder, or a
decoder depending on the position of the
DOLBY
Switch
(Figures
1-1
and
3-9).
The high-level input signals are concurrently
applied to the SCOPE OUTPUT Jacks and to the
Dolby decoder, through the TAPE MONITOR
Switch and PLAY CAL Controls. The decoder
functions as a flat amplifier, or a decoder, de-
pending on the position of the DOLBY Switch,
the TAPE MONITOR Switch, and the TAPE
COPY Switches (Figure 1-1). The output signal
of the decoder is monitored by the Dolby Level
VU Meter and applied to the MODE Switch.
The MODE Switch determines the manner in
which the left- and right-channel signals of the
program source are applied in the Model 3800:
LEFT channel only, RIGHT channel only, two-
channel STEREO, STEREO REVERSE, or
L+ R (left and right channels combined). The
signal selected by the MODE Switch is then
applied to the BALANCE Control. The
BALANCE Control adjusts the relative signal
level of the left and right channels by attenuating
the level of one channel while maintaining the
level of the other. From the BALANCE
Control, the signal is applied to the VOLUME
Control, which varies the level of the output
signal available at the PREAMPLIFIER OUT-
PUT Jacks.
The signal is also applied to the Loudness
Contour Circuit which, when activated, boosts
low and high frequencies at low listening levels
so that all frequencies appear to have equal
loudness. The Loudness Contour Circuit adjusts
the frequency response of the Model 3800 to
compare with the Fletcher-Munson loudness
curves (Section 2). The signal from the
VOLUME Control is then applied to the input
of the Times-Ten (X10) Amplifier Circuit.
The X10 Amplifier increases the signal level to
that required to drive power amplifiers. The
output of the X10 Amplifier is applied to an
Active Filter Network comprised of three filter
circuits (30Hz, 5KHz and 9KHz) and a Filter
Amplifier.
The
Active
Filter
Network
sharply
reduces
low-
and/or
high-frequency
noise
that
may
originate
at
the
program
source.
The
out-
put
of
the
Filter
Amplifier
is
then
applied
to
the
Tone
Control/Turnover
Network
(BASS,
MID
and
TREBLE
Tone
Controls),
the
250Hz
and
the
4KHz
TURNOVER
circuitry,
and
a
Tone
Amplifier
stage
(through
the
TAPE
REC-EQ
Switch).
The
output
of
the
Filter
Amplifier
after
TAPE
REC-EQ
is
also
applied
to
the
TONE DEFEAT Switch.
The
Tone
Control/Turnover
Network
performs
a
dual
function:
the
tone
control
portion
of
the
network
boosts
or
attenuates
low,
middle
and
high
frequencies;
the
turnover
portion
of
the
network,
when
activated,
decreases
the
point
at
which
low
frequencies
are
affected
by
the
BASS
Control
(250Hz)
and
increases
the
point
at
which
high
frequencies
are
affected
by
the
TREBLE
Control
(4KHz).
The
TONE
DEFEAT
Switch
selects
either
the
flat
output
of
the
Filter
Amplifier
(bypassing
the
tone
controls)
or
the
tone-control-altered
output
of
the
Tone
Amplifier.
From
the
TONE:
DEFEAT
Switch,
the
signal
is
applied
to
the
Time
Delay
Relay.
The
circuit
associated
with
the
Time Delay
Relay
holds.the
relay
contacts
open
for
approx-
imately
five
seconds
after
power
is
appied
to
the
Model
3800.
After
the
power
supply
circuits
have
stabilized,
the
relay
contacts
close.
Audible
“pops”
that
may
arise
from
p
ower
supply
transients
are
thereby
eliminated.
From the relay contacts the signal is appied to
the PREAMPLIFIER OUTPUT Jacks and con-
nected to drive an external power aml ifier.
The
power
amplifier
outputs
are
connecied
to
the
SPEAKER
SWITCHING
INPUTS
Terminals
and
the
signal
is
applied
to
the
stereo
PHD
NES

IN
PROGRAM
SELECTOR
OUT
PHONO
1
IN
Cc
A.
0201
Q203
205
207
209
PHONO 2 IN Cc
pes
PHONO/MI'
AMPL,
PHONO/MIC
EQUALIZATION)
t.
BFR
TO
TAPE
REC-EQ
SW
BUFFER
AMPL
MIC IN
TO
TAPE
REC-EQ
SW
RCD
LVL
CONT
TONE
CONTROL/TURNOVER
NETWORK
501
TUNER
IN
ACTIVE
FILTER
NETWORK
u201
211
30 Hz 9 KHz 5 KHz
FILTER FILTER FILTER
AUX
IN
-
A
CIRCUIT
CIRCUIT
CIRCUIT,
DOLBY
eNcopeR /o
DECODER
FEEDBACK
TAPE
TIN
&
CIRCUIT
P
=
TAPE
21N
(céstwer)
me
TURNOVER
°
FILTER
Ds
CIRCUITS
DUBBING IN
FROM L CHAN
DUBBING
OUT
a
°
TO
RIGHT
CHANNEL
0
DOLBY
° 9
BALANCE
TAPE
1
OUT
pecourn
9
FROM R CHAN 1]
5
. 4
'
TAPE2OUT
=
SIDE
CHAIN
|
i
INPUT
a
:
H
ad
SCOPE
CUT
Cc
DOLBY:
'
[votume]
.
10
R
CHAN
METER
TtRo
S
0
acca
STEREO REVO i
=
H
SPEAKER
STEREOO
&
'
|
SWITCHING
t
1
RIGHTO
¥
‘st
LOUDNESS
INPUTS
Lert
‘SS
CONTOUR
@
™
CIRCUIT
‘0
af
oo
0
-O—
Pra
PRIAMP
COUT
SPEAKERS
out
«LOUDNESS
}>
IN
REMOTE
SPEAKERS
PHONES
Figure
1-1
Functional
Bhck
Diagram
1-3

LS
A100 CONTROL BOARD
P/N 200-2002-100
CHASSIS FRONT
CHASSIS BASE
A500 DOLBY/TAPE
MONITOR BOARD
P/N 200-2003-100
7 CONDUCTORS (TWISTED)
3 CONDUCTORS (TWISTED)
A200/300 PREAMPLIFIER BD 3 CONDUCTORS (TWISTED)
OO O O PIN 200-2009-100
3 CONDUCTORS (TWISTED)
A200/300 PREAMPLIFIER BOARD
P/N 200-2009-100
CHASSIS REAR
A500 DOLBY/TAPE
MONITOR BOARD
P/N 200-2003-100
©@
A400 JACK INPUT PANEL
P/N 200-2005-110
©O
NOTES :
7 CONDUCTORS (TWISTED)
Figure 1-2 Wiring Diagram
1-4
2. FOR SCHEMATIC SEE FIGURE 39.
3800 EXPORT ONLY
220V CONVERSION
NOTE:
FOR 100V CONVERSION
CONNECT VIO JUMPER TO
WHT/YEL TRANSFORMER LEAD
ON TB6.
1. FOR COMPONENT IDE. TIFICATION REFER TO PARTS LIST.
a
u
z
e
=
=

TAPE
TAPE
TAPE
OUT
TAPE
IN
COPY
MONITOR
(TO
RECORDER)
|(FROM
RECORDER)
OUT
POSITION
POSITION
OUT
SOURCE
1——+ 2
DOLBY SWITCH
DOLBY
F
ANAL
MULE
KU
UY
WU
RUNS
AIAIAIA
NOTES:
Dolby
FM
position
pre-
Signal
from
empts
all
other
program
recorder
No.
1
SOURCE
sources.
XY
NN
1. Dolby encoder in flat
amplifier mode.
UX
RUS
x
2——+ 1
2. Dolby decoder in Si
gnal from NY
decode
mode.
recorder
No.
2
SOURCE
Ap
<|
3. ame
Decoded signal
XY?
RUN
IY
Flat
signal
SOURCE
lu
AINAIATATA
Fiat Dolby Processed signal
Ez
IL
XX
X
My
UX
NUR
i
Rt
RNS
AIAIA
SOURCE
SOURCE
NOTES:
an
Ue
Ne
X
NUS
NNN
X
1. Dolby encoder in
flat amplifier mode.
x
2. Dolby decoder in
decode amplifier mode.
Signal from
recorder No.
tee fs
I
UU
x
x
NUS
Rae
ALATATATATAJALA
XL
X
SOURCE
it
ie
X
Kk
KI
X
XY)
Figure
1-3
Dolby
NR
Circuit
Signal
Processing
Diagram
1-5